• Christoffer Dall's avatar
    mm: Fix PageHead when !CONFIG_PAGEFLAGS_EXTENDED · ad4b3fb7
    Christoffer Dall authored
    Unfortunately with !CONFIG_PAGEFLAGS_EXTENDED, (!PageHead) is false, and
    (PageHead) is true, for tail pages.  If this is indeed the intended
    behavior, which I doubt because it breaks cache cleaning on some ARM
    systems, then the nomenclature is highly problematic.
    
    This patch makes sure PageHead is only true for head pages and PageTail
    is only true for tail pages, and neither is true for non-compound pages.
    
    [ This buglet seems ancient - seems to have been introduced back in Apr
      2008 in commit 6a1e7f77
    
    : "pageflags: convert to the use of new
      macros".  And the reason nobody noticed is because the PageHead()
      tests are almost all about just sanity-checking, and only used on
      pages that are actual page heads.  The fact that the old code returned
      true for tail pages too was thus not really noticeable.   - Linus ]
    Signed-off-by: default avatarChristoffer Dall <cdall@cs.columbia.edu>
    Acked-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Will Deacon <Will.Deacon@arm.com>
    Cc: Steve Capper <Steve.Capper@arm.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: stable@kernel.org  # 2.6.26+
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    ad4b3fb7